I looked at your PMID and wow, that is an insane number of authors.
I’d say contact RefMan tech support to find out if there is a hard limit of authors, or any workarounds. You might not be able to do anything.
Will it let you download more authors if you save the PubMed record as a text file and use the import filter vs. the automatic import?
Practically, will your output style truncate the author list anyway? If yes, I’d just save the PubMed record as a text file, manually delete most of the author names, then import. Or enter the record and the first few authors manually.You can enter an et al. at the end of the author list by entering =et al.;